Why is Siding flashing alongside windows is called J-molding?

Siding flashing alongside Windows is called J-molding because of its distinctive "J" shape, which allows it to effectively channel water away from the window and protect the underlying materials from moisture intrusion. This design also provides a clean, finished look around Windows, ensuring that the siding fits snugly against them while accommodating expansion and contraction. Additionally, J-molding helps to secure the siding in place, providing structural support and enhancing the overall durability of the installation.